Cement finishing machine



y 26, 1959 M. E. WHITEMAN 2,887,934

CEMENT FINISHING MACHINE Filed April 6, 1956 4 Sheets-Sheet 1 o N 0 BY K; N 3 N "R N r N N imam/54s y 1959 M. E. WHITEMAN 2,887,934

,CEMENT FINISHING MACHINE 4 Sheets-Sheet 2 Filed April 6-, 1956 5 N w, MW 3 NE 2 WM m WW W 5. W 2% V W W M. E. WHITEMAN CEMENT FINISHING MACHINE May 26, 1959 4 Sheets-Sheet 3 Filed April 6, 1956 5 m u, w Mm TE 0 a 5 W f V m M y 1959 M. E. WHlTEMAN 2,887,934

CEMENT FINISHING MACHINE Filed April 6, 1956 4 Sheets-Sheet 4 lh-lllllllll annex/5V9 United States Patent 2,887,934 Patented May 26, 1959 CEMENT FINISHING MACHINE Marvin E. Whiteman, Pacoima, Calif.

Application April 6, 1956, Serial No. 576,664

6 Claims. (Cl. 94-45) This invention relates to cement finishing machines, and included in the objects of this invention are:

First, to provide a cement finishing machine which employs two rotors having radiating troweling blades, the blades of the two rotors being so related and operated that the reaction forces between the blades and the cement are substantially cancelled out. As a consequence, there is no strong tendency of the machine to travel over the cement surface, but instead the machine may be guided and manipulated by the operator with a minimum of effort.

Second, to provide a cement finishing machine having two sets of counterrotating troweling blades, wherein a convenient control on the guiding handle of the machine effects simultaneous and equal adjustment of all the blades to various angular positions relative to the cement surface, so as to control and vary the finishing operation.

Third, to provide in a dual rotor cement finishing machine a simple and effective means of adjusting the troweling blades individually, as well as adjusting one set of troweling blades relative to the other.

Fourth, to provide a cement finishing machine having a novel drive mechanism disposed in a compact housing, which also supports the motor to drive the machine and the control means.

Fifth, to provide a dual rotor cement finishing machine having a drive housing extending between the rotors and a peripheral guard rail suspended above the rotors by supporting bars secured to the extremities of the housing.

With the above and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawings in which:

t Figure l is a perspective view of the cement finishing machine;

Fig. 2 is an enlarged, fragmentary, perspective view thereof, with the motor removed and with a portion of the housing cover broken away;

Fig. 3 is an enlarged, partial sectional, partial elevational view taken along the line 33 of Fig. 2;

. Fig. 4 is a sectional view taken along the line 44 of Fig. 3, showing particularly the troweling blade control means;

Fig. 5 is a fragmentary sectional view taken through 55 of Fig. 3;

Fig. 6 is a fragmentary sectional view through 66 of Fig. 3;

Fig. 7 is a fragmentary view taken along the line 77 of Fig. 4, showing a troweling blade in its flat position;

Fig. 8 is a view similar to Fig. 7, showing the troweling blade in its inclined position; and

Fig. 9 is a fragmentary, longitudinal, sectional view of the outer end of the handle shaft.

The cement finishing machine includes a housing structure 1 which is relatively narrow with respect to its length, wider at its central portion and tapering towards its ex tremities. The housing structure is provided with peripheral side walls 2 and is provided at its central portion with a gear box 3. The extremities of the housing structure form vertically disposed bearing compartments 4. The bearing compartments and central gear box are rigidly joined by webs 5 which also join the side walls 2 Extending transversely through the gear box 3 of the housing structure 1 and mounted in suitable bearings is a drive shaft 6 on which is mounted a worm 7. The worm 7 drives a pair of worm gears 8 disposed on opposite sides thereof and mounted on vertical shafts 9 journaled between bearings 10. The upper bearing of each shaft 9 is mounted in the upper wall of the gear box 3, whereas the lower of each bearing is mounted in a cover plate 11 secured to the underside of and closing an access aperture to the gear box 3.

The shafts 9 protrude from the upper side of the gear box 3 and are provided with sprockets 12, which are connected by chain drives 13 to sprockets 14 mounted on rotor shafts 15 and journaled in bearing assemblies 16 fitted within the bearing compartments 4. The side walls 2 of the housing structure 1 project above the bearing compartments 4 and the central gear box 3, and a cover plate 17 overlies the housing structure so as to enclose the sprockets 12 and 14 and the chain drives 13.

The rotor shafts 15 extend downwardly from the housing structure 1. Secured to their lower ends are hub members 18. Each hub member comprises a stem 19 suitably keyed to the shaft 15 and a bottom end flange 20. The end flange supports radiating journals 21 which may be integral therewith. In the construction illustrated, three such journals radiate from each hub member 18.

Each journal 21 receives a troweling blade shaft 22 which extends radially therefrom. The radially extending portion of each shaft is preferably square or rectangular in cross-section and is adapted to be bolted to a central rib 23 secured to a troweling blade 24. Each troweling blade is in the form of a rectangular sheet metal plate. By reason of the journal connections of the shafts 22, the troweling blades are capable of tilting movement about the axes of the journals 21.

The radially inner ends of the journals 21 are spaced from the stem 19, and the radially inner ends of the shafts 22 are provided with laterally directed control arms 25, the extremities of which are provided with upwardly directed set screws 26. A

Slidably mounted on each rotor shaft 15' is a control collar 27 having a collar portion 28 suitably keyed to the rotor shaft by a key pin 29. Each control collar includes a flange 30 which overlies the corresponding hub member 1. The underside of the flange 30 engages the set screws 26 of the corresponding control arms 25 so that axial movement of each control collar causes a tilting action of the corresponding troweling blade, as shown in Figs. 7 and 8. A yieldable skirt 31 depends from the flange 30 and extends to the peripheral portion of the bottom flange 20 of the corresponding hub member 18.

Each control collar 27 is provided with a thrust bearing 32 which is engaged by a yoke 33 carried at the end of a shaft 34. The two shafts thus provided are disposed in coaxial relation and are supported at their ends adjacent the yokes 30 by journal brackets 35. One of the shafts 34 is provided with a collar 36 fixed thereto, whereas the adjacent end of the other shaft is journaled therein. This journaled shaft is likewise provided with a collar 37 secured thereto adjacent the collar 36.

The two collars 36 and 37 are provided with lugs 38 and 39 which overlap axially. A set screw 40 extends between the lugs 38 and 39 so that the shafts 34 may be adjusted circumferentially relative to each other. Extending from the collar 36 is a lever arm 41.

Secured to one side of the housing structure 1' is a handle-supporting bracket 42 in which is mounted a tubular handle shaft 43. A control cable 44 is attached to 3 the lever arm 41 and extends therefrom about a pulley 45 carried by the bracket 42 and into the handle shaft 43.

The upper end of the cable-44 is secured within a sleeve 46 which is slidablyrmounted within thehandle bymeans of a-set screw 47 and an axial slot formed in the handle shaft 43, as shown in Fig. 9. The extremity of the handle shaft 43 is provided with a bearing 48 in which is journaled a screw shaft 49 screw-threaded into the sleeve 46. The screw shaft 49 is provided at its outer extremity with a control knob 50. The upper-end of the handle shaft 43 is provided with laterally extending handle arms 51 having .grips 52 at their extremities.

Supported on the housing structure 1 is a conventional motor 53, which may be an internal combustion engine or an electric motor. In either case, the motor is connected by a belt drive which includes a sheave 54 mounted on the protruding end of the drive shaft 6. If an internalcombustion engineis employed, a suitable throttle cable 55 extends therefrom to a convenient location on the handle shaft 43 and is attached to a suitable throttle lever 56.

The troweling blades 24 define circular areas which overlap and are so positionedrelatively that the blades, as they pass about the near sides of their circular paths, intermesh but do not touch each other. A guard rail 57 extends around the far sides of the circular areas defined by the troweling blades and then-extends tangentially between these areas.

The guard rail 57 is suspended above the tips of the troweling blades 24 by means of braces 58. Three such braces extend radially inwardly and upwardly from each semicircular end of the guard rail and are joined to a common U-shaped mounting strap 59 which is secured to a corresponding end of the housing structure 1. The mounting straps 59 are preferably set into recesses formed in the side walls 2 so as to provide a rigid support for the braces 58 and the guard rail 57.

Operation of the cement finishing machine is as follows:

The motor 53 operates through the drive shaft 6, worm 7, worm gears 8, sprockets '12, chain drives 13, sprockets 14, and rotor shafts to rotate the hub members 18 in opposite directions so that their near sides move in the same direction.

The troweling blades 24 move about circular areas which overlap, and in doing so apply a torsional reaction force to the housing structure 1. However, the reaction force produced by each set of troweling blades is in opposition to the reaction force produced by the other set, so that there is no substantial tendency for the machine to travel across the cement surface on which the troweling blades are used. As a consequence, an operator having control of the handle shaft 43 may easily guide the machine in any desired direction; forward, backward, or endwise.

The operator may readily change the angular position of the troweling blades 24 simultaneously by turning the control knob 50 which moves the sleeve 46 axially so as to pull on the control cable 44 or release the cable. That is, movement of the troweling blades to a flat position, such as shown in Fig. 7, is accomplished by the weight of the machine, Whereas the tension of the cable is employed to tilt the blades by movement of the lever arm 41, shafts 34, yokes 33, control collars 27, and control arms 25.

By reason of the set screws 26-provided on the control arms 25, the angular position of each troweling blade in its set may be adjusted. By adjustment of the set screw 40, the relative angular position of the two shafts 34 may be adjusted so that the angular position of both sets of troweling blades maybe identical. This is highly important, for the reason that the difference inthe angular position of the troweling blades would not only create an unbalanced reaction force, tending to cause the machine to travel on the cement surface, but would not produce a uniform finishing operation.

In practice the troweling blades 24 are first set in a substantially inclined position, such as shown in Fig. 8, to effect a rough finishing, and then are moved to the fiat position, shown in Fig. 7, to provide a fine finish. By terminating the finishing operation at any selected angular position of the troweling blades, the texture of the finished concrete surface may be controlled.

While a particular embodiment of this invention has been shown and described, it is not intended to limit the same to the exact details ofthe construction set forth, and it embraces such changes, modifications, and equivalents of the parts and their formation and arrangement as come within the purview of the appended claims.

I claim:

1. A cement finishing machine, comprising: a housing structure; a pair of rotor shafts depending from said howing; a rotor hub at the lower end of each shaft; a set of troweling blades pivotally connected to said hub for tilting movement about axes radiating from said hub, said sets of troweling blades defining intersecting circular areas, and the troweling blades of each set relatively spaced to intermesh as they rotate; means for rotating said sets of troweling blades in opposite directions about the axes of said shafts; and means for simultaneously and similarly tilting the troweling blades of both of said sets.

2. A cement finishing machine as set forth in claim l, wherein said tilting means comprises: a collar slidably mounted on each rotor shaft; lever arms extending from said troweling blades engageable by said collars; a pair of coaxial operating shafts extending between said rotor shafts; lever means connecting said operating shafts with said collars; means for adjusting the relative circumferential position-of said operating shafts to adjust relative position of said collars; and means between said lcvcr arms and said collars for adjusting relative position of said troweling blades.

3. A cement finishing machine, comprising: a housing structure; a pair of rotor shafts depending from said housing; a rotor hub at the lower end of each shaft; a set of troweling blades pivotally connected to each of said hubs, for tilting movement about axes radiating from said hubs, said sets of troweling blades defining intersecting circular areas, and the troweling blades of each set relatively spaced to intermesh as they rotate; means for rotating said sets of troweling blades in opposite directions about the axes of said shafts; means for adjusting the relative angular position of each troweling blade in its set; means for adjusting as a unit the angular position of the troweling blades of one set relative to the other set; and means for tilting all of said troweling blades simultaneously.

4. A cement finishing machine, comprising: an elongated housing structure; a central transversely extending drive shaft; a drive worm thereon; a pair of worm gears on opposite sides of said drive worm; a pair of rotor shafts at the extended ends of said housing structure and projecting downwardly therefrom; drive means connecting said worm gears and rotor shafts to drive said rotor shafts in timed relation with each other; a rotor hub at the lower end of each shaft; a set of troweling blades pivotally connected to said hub for tilting movement about axes radiating from said hub, said sets of troweling blades defining intersecting circular areas, and the troweling blades of each set relatively spaced to intermesh as they rotate; means for rotating said sets of troweling blades in opposite directions about the axes of said shafts; and means for simultaneously and similarly tilting the troweling blades of both of said sets.

5. A cement finishing machine as set forth in claim 4, wherein said tilting means comprises: a collar slidably mounted on each rotor shaft; lever arms extending from said trowelingblades engageable by said collars; a pair of coaxial operating shafts extending between said rotor shafts; lever means connecting said operating shafts with said collars; means for adjusting the relative circumferential position of said operating shafts to adjust relative position of said collars; and means between said lever arms and said collars for adjusting relative position of said t-roweling blades.

6. A cement finishing machine, comprising: an elongated housing structure; a central transversely extending drive shaft; a drive worm thereon; a pair of worm gears on opposite sides of said drive worm; a pair of rotor shafts at the extended ends of said housing structure and projecting downwardly therefrom; :drive means connecting said worm gears and rotor shafts to drive said rotor shafts in timed relation with each other; a rotor hub at the lower end of each shaft; a set of troweling blades pivotally connected to said hub for tilting movement about axes radiating from said hub, said sets of troweling blades defining intersecting circular areas, and the troweling blades of each set relatively spaced to inter-mesh as they rotate; means for rotating said sets of troweling blades in opposite directions about the axes of said shafts; means for simultaneously and similarly tilting the troweling blades of both of said sets; and means for adjusting the relative angular position of each troweling blade in its set.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Engineering News Record, May 19, 1955, page 52. 

